As a mainland Chinese with some knowledge about Chinese film market.I think you misunderstanding the Chinese audiences.Transformers are popular in China as it was one of the few foreign cartoons can be released in China.Chinese audiences know Transformers for more than 25years.It has a huge fanbase.
Pacifc Rim make much just because it is the only hollywood blockblaster release about the same time in China and the US,so no illegal copy,in China.In fact Chinese likes movies such as Titanic most

I think people underrate Transformers a lot.I see a lot of hate for it on the internet.But almost every movie makes so much money.People see movies for being entertained and Michael Bay movies do that.